No abstract

To better understand the response of oxygen vacancy concentration to applied potential, the lattice parameter of pulsed laser deposited La 0.6 Sr 0.4 Co 1-x Fe x O 3-thin films was monitored using in situ X-ray diffraction. We demonstrate that the chemical expansion under applied potential depends on the cathode morphology, which determines the contribution of different reaction pathways. We investigated applied potential dependent lattice expansion on La 0.6 Sr 0.4 Co 1-x Fe x O 3-with 3 different Co:Fe ratios in an attempt to connect bulk chemical expansion data to thin films. We find that the chemical expansion trends in thin films are different than expected from bulk data.

Electron channeling contrast imaging (ECCI) was used to characterize coherently strained La0.7Sr0.3MnO3 (LSM) films grown on (110)cubic-SrTiO3 (STO) and (100)orthorhombic-NdGaO3 (NGO). We focus on the characterization of a relatively low density (1–3 μm/μm2) of meandering loops (MLs) found in the LSM film on STO and absent in the film on NGO. The MLs exhibit a uniform contrast variation from the background and a strong contrast dependence on the diffraction vector g. The MLs are quantitatively consistent with LSM anti-phase boundaries (APBs) having a displacement vector R=12[001]LSM. These APBs are consistent with a “double positioning” degeneracy of tilted octahedra along [001]LSM on untilted octahedra along [001]STO. The results highlight the non-destructive capacity of ECCI to characterize extended defects in oxide films.

Electronic, magnetic, electrochemical properties of functional oxide materials depend critically on the presence of extended defects [1]. In addition to traditional techniques such as transmission electron microcopy (TEM) and X-ray diffraction (XRD), recent developments in electron channeling contrast imaging (ECCI) have enabled non-destructive analysis of extended defects on the mesoscale [2,3]. Combining these techniques offer unique advantages to further understanding extended defect generation and their potential impacts on functional properties in oxide materials.